Hemodynamics of cor pulmonale

Long-term exposure to biomass fuel and its relation to systolic and diastolic biventricular performance in addition to obstructive and restrictive lung diseases

BACKGROUND

Previous studies have demonstrated an increased risk for cardiovascular events and pulmonary disease in patients with biomass fuel exposure (BFE). However, biventricular heart function has yet to be investigated in these patients. Left ventricular (LV) myocardial performance index (LVMPI), which is an index of global ventricular function, incorporates ejection, isovolumic relaxation, and contraction times. In this study, pulmonary function and biventricular heart function were investigated in nonsmoking female patients with BFE.

METHODS

Our study population consisted of 46 female patients with BFE (group 1) and 31 control subjects (group 2). Pulmonary function tests and transthoracic echocardiographic examination were performed. Right ventricular myocardial performance index (RVMPI) and LVMPI were obtained by tissue Doppler imaging echocardiography (TDI).

RESULTS

BFE caused obstructive and restrictive spirometric impairments. RVMPI was higher in group 1 (0.55 ± 0.07) than group 2 (0.46 ± 0.06) (P = 0.042) and LVMPI was higher in group 1 (0.54 ± 0.08) than group 2 (0.47 ± 0.05) (P = 0.032). Also, pulmonary artery systolic pressure was higher in group 1 than group 2 (P = 0.02).

CONCLUSIONS

BFE causes both obstructive and/or restrictive lung disease and systolic and diastolic biventricular dysfunction. Nonetheless, long-term studies are needed to understand on BFE-related ventricular dysfunctions and to document subsequent cardiovascular events.

Percent emphysema, airflow obstruction, and impaired left ventricular filling

BACKGROUND

Very severe chronic obstructive pulmonary disease causes cor pulmonale with elevated pulmonary vascular resistance and secondary reductions in left ventricular filling, stroke volume, and cardiac output. We hypothesized that emphysema, as detected on computed tomography (CT), and airflow obstruction are inversely related to left ventricular end-diastolic volume, stroke volume, and cardiac output among persons without very severe lung disease.

METHODS

We measured left ventricular structure and function with the use of magnetic resonance imaging in 2816 persons who were 45 to 84 years of age. The extent of emphysema (expressed as percent emphysema) was defined as the percentage of voxels below -910 Hounsfield units in the lung windows on cardiac computed tomographic scans. Spirometry was performed according to American Thoracic Society guidelines. Generalized additive models were used to test for threshold effects.

RESULTS

Of the study participants, 13% were current smokers, 38% were former smokers, and 49% had never smoked. A 10-point increase in percent emphysema was linearly related to reductions in left ventricular end-diastolic volume (-4.1 ml; 95% confidence interval [CI], -3.3 to -4.9; P<0.001), stroke volume (-2.7 ml; 95% CI, -2.2 to -3.3; P<0.001), and cardiac output (-0.19 liters per minute; 95% CI, -0.14 to -0.23; P<0.001). These associations were of greater magnitude among current smokers than among former smokers and those who had never smoked. The extent of airflow obstruction was similarly associated with left ventricular structure and function, and smoking status had similar modifying effects on these associations. Percent emphysema and airflow obstruction were not associated with the left ventricular ejection fraction.

CONCLUSIONS

In a population-based study, a greater extent of emphysema on CT scanning and more severe airflow obstruction were linearly related to impaired left ventricular filling, reduced stroke volume, and lower cardiac output without changes in the ejection fraction.

Echocardiographic evaluation of left and right ventricular diastolic function in patients with chronic obstructive pulmonary disease

The aim of this study was to investigate the effects of chronic obstructive pulmonary disease (COPD) on left ventricular and right ventricular diastolic and systolic functions. Forty-eight patients with severe COPD were studied. Patients were divided into 2 subgroups according to pulmonary artery pressures: 25 patients with pulmonary hypertension (group 1) and 23 patients with normal pulmonary artery pressure (group 2). As a control group, 59 normal subjects were studied (group 3). Patients in group 1 had higher tricuspid peak A velocity, lower tricuspid E velocity, longer isovolumetric relaxation time, higher mitral A wave, lower mitral E wave, and slower color propagation velocity than groups 2 and 3. There was no significant difference between left ventricular diastolic filling parameters between groups 2 and 3. Patients with COPD and pulmonary hypertension have left and right ventricular diastolic dysfunction. However, patients with COPD and normal pulmonary artery pressure have normal left and right ventricular diastolic function.

Production and reversibility of right ventricular hypertrophy and right heart failure in dogs

Combined heart-lung transplantation has been used for end-stage primary pulmonary hypertension. Experience with single-lung transplantation for other conditions suggested that associated severe right ventricular dysfunction resulting from increased afterload would recover after placement of a satisfactory lung allograft. Early experience with the application of single-lung transplantation for pulmonary hypertension supports this contention. We devised a reversible canine model of chronic progressive pressure-overloaded right heart failure by pulmonary artery banding to study the echocardiographic, hemodynamic, and pathological reversibility of the failing right heart. Clinical right heart failure was defined as the development of ascites and pleural effusions. Right heart failure developed in 23 dogs 67 to 348 days after banding, and they were divided into two groups to determine its early and long-term effects. Group 1 dogs (n = 11) were either sacrificed immediately after the onset of right heart failure (n = 5) or unbanded (n = 6); group 2 dogs (n = 12) were maintained in right heart failure for 3 months and then either sacrificed (n = 6) or unbanded. Unbanded dogs in both groups were observed for 4 additional months before sacrifice. A control group of 6 normal dogs was sacrificed for pathological comparisons. After unbanding, the right ventricular systolic pressure fell from 97 +/- 17 mm Hg (group 1) and 88 +/- 31 mm Hg (group 2) to 44 +/- 11 mm Hg and 47 +/- 13 mm Hg, respectively. Despite this persistent gradient across the pulmonary artery, echocardiographic and hemodynamic measures of right ventricular function returned to normal, albeit more slowly in the group 2 dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic pressure overload on the maximal rate of pressure fall of the right ventricle

The maximal rate of fall in right ventricular pressure (negative dp/dt) was evaluated in 34 patients. Eight had normal pulmonary arterial pressure. Seventeen had pulmonary arterial hypertension, and nine had pulmonary arterial hypertension with right ventricular failure. The right ventricular maximal negative dp/dt in patients with normal pulmonary arterial pressure was 170 +/- 20 mm Hg/sec. In patients with pulmonary arterial hypertension not accompanied by right ventricular failure, this value was 670 +/- 60 mm Hg/sec; and in patients with right ventricular failure, it was also 670 +/- 60 mm Hg/sec. This was higher than in control subjects (P less than 0.001). The maximal positive dp/dt was also higher in patients with pulmonary hypertension, regardless of the presence of right ventricular failure. Right ventricular maximal negative dp/dt correlated with right ventricular maximal positive dp/dt (r = 0.72). Right ventricular maximal negative dp/dt in patients who were not in right ventricular failure correlated linearly with pulmonary arterial systolic pressure (r = 0.83) and pulmonary arterial diastolic pressure (r = 0.83). At any level of pulmonary arterial systolic pressure, right ventricular maximal negative dp/dt in patients with right ventricular failure was lower than in patients with the same level of pulmonary arterial hypertension who were not in failure. These observations indicate that right ventricular maximal negative dp/dt is dependent on load. Even in the presence of right ventricular failure, right ventricular maximal negative dp/dt exceeded values in control subjects.

Performance of the failing and nonfailing right ventricle of patients with pulmonary hypertension

Hemodynamic performance of the right ventricle was measured in 34 patients: 17 with pulmonary hypertension, 9 with pulmonary hypertension and right ventricular failure and 8 control subjects. Among the patients with pulmonary hypertension who did not have right ventricular failure, right ventricular maximal isovolumic rate of development of ventricular pressure (dP/dt) was significantly elevated (P less than 0.001), whereas maximal 1/P dP/dt and maximal velocity of contractile element shortening (Vmax) were comparable with values observed in control subjects. The patients with pulmonary hypertension who had right ventricular failure also showed an augmented right ventricular maximal dP/dt (P less than 0.001) and normal 1/P dP/dt and Vmax. These observations indicate that in pulmonary hypertensive heart disease, even when the right ventricle failed in a clinical sense, the contractile effort was normal. Consequently, right ventricular failure may develop in patients with pulmonary hypertensive heart disease even though the cardiac muscle performs normally as a contractile tissue.

Left ventricular function in patients with chronic obstructive pulmonary disease

Left ventricular function was assessed in six patients with essentially normal cardiopulmonary function, in five patients with primary myocardial disease, and in 16 patients with chronic obstructive pulmonary disease by determining the response of the ventricle to an increased resistance to ejection. Studies were performed at the time of cardiac catheterization and increased resistance to left ventricular ejection was produced by the intravenous infusion of methoxamine. In the control patients, methoxamine produced an increase in stroke volume index (SVI), in stroke work index (SWI), and stroke power index (SPI), whereas left ventricular end-diastolic pressure (LVEDP) increased only moderately. In contrast SVI, SWI, and SPI fell, whereas LVEDP increased inordinately in the patients with myocardiopathy. The patients with chronic obstructive pulmonary disease responded to the infusion with an increase in SVI, SWI, SPI, and LVEDP comparable to the control patients. Furthermore, in this latter group of patients, a quantitatively similar response was observed in those with essentially normal resting hemodynamics, in those with resting pulmonary hypertension, and in those whose disease had progressed to the stage of right ventricular failure. This study provides no evidence that chronic obstructive pulmonary disease results in chronic impairment of left ventricular function, but on the contrary, has demonstrated that the left ventricle responds normally to an increased pressure load in these patients.